SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd60d1819046548731777ea10f6a7f53f5eafc9d75a719248be23913c18866960' 
  AND token = '37tvzka5Cxx5nXogSrB3SfWe2tAeO+bRHc7aoDMBIXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}